It is common in the wire manufacturing industry to produce a continuous length of wire which is cut into segments having desired, shorter lengths, and which are then coiled into a convenient packaging form. It is known in the art how to cut and coil wire in individually distinct and separate process steps. However, it is not known how to cut a length of moving wire into a succession of wire segments without interrupting the movement of the wire or the segments, and then, in the same continuous process sequence, coil these wire segments while they travel downstream at the same speed. The inability to combine these two steps into one continuous step results in significant costs which are incurred when the wire segments are separately moved from the cutter to the coiler.
U.S. Pat. No. 1,304,034 shows an apparatus which continuously cuts a length of moving wire into wire segments. However, this apparatus is not designed for high speed automated cutting of wire, since it requires manual operation to engage the cutting surfaces to sever the wire. The wire must be moving slow enough so that an operator will know when to cut the wire; even then, the wire segments which are cut may not have the precise lengths desired. Additionally, continual sliding contact between several components of this machine during the cutting operation may result in early wear, which may decrease the operating efficiency and accuracy of the cutter. Other U.S. patents of more general interest as regards the state of the art in wire cutting are: U.S. Pat. Nos. 2,401,639, 2,541,948, 3,057,239, 3,561,311, 3,477,326 and 4,065,992.
In a continuous wire fabrication operation, it is common to divert successive segments of wire to duplicate machines at different work stations. This allows one machine to perform its function on one segment of wire while the next segment of wire is diverted to another machine. See U.S. Pat. Nos. 2,126,528, 2,944,755, 3,223,345, 3,704,839, and 3,941,329. A common feature of the apparatus used to divert wire is a first wire pathway which is moved to direct successive wire segments through alternate, diverging second wire pathways which then direct the wire to different work stations. The position of the first wire pathway with respect to each of the second wire pathways must be maintained until the tail end of a moving wire segment has passed completely out of the first wire pathway and passed into the second wire pathway. A switching mechanism then moves the first wire pathway into another position, to direct the next wire segment through a different second wire pathway. The tail end of one wire segment must be spaced from the lead end of the next wire segment a distance which corresponds to the time it takes the first wire pathway to move to its next position. This space between wire segments may be created by stopping the movement of the wire briefly after each segment is cut, or, the segments may be held and then released at the proper time to obtain the correct separation distance. Regardless of the relative switching speeds and wire speeds, the first wire pathway must be moved to its respective position with precisely timed accuracy in order to avoid directing the wire into the wrong pathway, and to prevent wire jams in the diverter apparatus. Any error in the switching operation can result in significant system downtime.
One method for transporting wire from one work station to another, such as from a cutter to a coiler, is to push the wire through ducts located between each work station. However, when pushing wire through these ducts, the wire has a tendency to buckle in the duct. Alternatively, frictional forces between the wire and the duct may either slow the movement of the wire, or cause it to become wedged in the duct so that it cannot move. Also, the wire may become damaged from excessive scraping against the inside surface of the duct as it travels through it. Various means have been devised to improve the ability to transport wire through these ducts. In U.S. Pat. No. 3,176,538, a self-lubricating polymeric material such as Teflon.RTM. is applied to the inside diameter of the duct and to the outside diameter of the wire being pushed through the duct to minimize friction between the wire and duct. In U.S. Pat. No. 4,426,046, a system of planetary roller drive mechanisms support the wire while it is pushed through the duct. This system imparts a roller-induced vibration to the wire, which drives the wire through the duct. However, such a vibrating system may damage the wire while it moves through the duct. Also, the system may be subject to downtime due to mechanical failure. Other U.S. patents which indicate the general state of the art in the field of wire transport are U.S. Pat. Nos. 4,196,333 and 4,265,025.
Machines for winding lengths of wire or strip material into coils are well known in the art. In general these coilers have a mandrel, rotated by a dedicated motor, onto which the wire is wound. Various means have been devised to attach the lead end of the moving wire to the mandrel at the start of the coiling process. These means commonly utilize endless belts which move around pulleys and partially surround the rotating mandrel, as shown in U.S. Pat. Nos. 2,890,003, 3,315,510, 3,328,991, 3,344,638, 3,423,981, and 3,988,916. The wire lead end is directed between the mandrel and the belt, and is captured therebetween; the coiling process begins as the mandrel is rotated. In some coilers, the endless belt is stationary and the mandrel is rotated as the lead end of the wire is fed between the belt and the mandrel the friction between the incoming wire and the belt propels the belt into motion. To avoid buckling in these prior art coilers, the initial wire speed and the mandrel speed must be slow until the belt is accelerated to a speed which matches the speed of the wire. Once the wire lead end has attached to the mandrel, the wire is firmly held in place and forced to conform to the shape of the mandrel due to pressure exerted on the wire by the belt. To maintain a constant coiling rate, the tangential speed of the coil outer surface must remain constant throughout the winding process; speed reduction means may be required to continually adjust the angular speed of the mandrel during the coiling process.
After the lead end is attached, and a number of wraps of the wire have been made on the mandrel, the belt is pulled away from the mandrel. Wire which does not fully plastically deform around the mandrel may unwind after the belt is removed. Additionally, after the coiling operation is completed, the unattached tail end of the wire may "whip" around the mandrel as the rotation of the mandrel is stopped. To prevent any contact of the whipping tail end with the surroundings, the coiling apparatus must be shielded.
If the wire is stopped or its speed is decreased as it is cut or coiled, or during any intermediate step, the efficiency of the wire processing operation is decreased. Also, if the wire is damaged, it must be discarded, which also decreases efficiency. Therefore, in order to maximize production efficiencies in a high speed wire cutting and coiling operation, it is required that the wire move continuously, without being damaged, and at a constant high speed through each process step and from one process step to the next. While it is known how to cut and coil wire, prior art cutting and coiling apparatus cannot meet these operating requirements.